An average of the last 303 days of Modis Terra’s arctic mosaics. (Postprocessing: convert -auto-level -modulate 100,180 -resize 768x -gamma 0.7.)

Update: I’ve been doing more work on this lately (September 2012) here. The above picture doesn’t use the fancy cloud-removal method described there – it’s a pure average with boosted contrast, so it essentially assumes that cloud cover is uniform, which of course it isn’t. (Seeing cloud cover patterns is interesting, but less interesting to me than recovering the ground color.)